The present invention relates to a rotary compressor including a driving element and a rotary compression element driven by a rotation shaft of this driving element, the elements being disposed in a sealed container.
Heretofore, this type of rotary compressor, for example, a multistage compression type rotary compressor including first and second rotary compression elements is constituted of a driving element and first and second rotary compression elements driven by a rotation shaft of this driving element, the elements being disposed in a sealed container.
As to the first and second rotary compression elements, the second rotary compression element is disposed on an upper side, and the first rotary compression element is disposed on a lower side via an intermediate partition plate. That is, the first and second rotary compression elements are constituted of: upper and lower cylinders disposed on and under the intermediate partition plate; rollers fitted into eccentric portions disposed on the rotation shaft with a phase difference of 180 degrees to eccentrically rotate in these cylinders; vanes which abut on the respective rollers to define the insides of the cylinders on low-pressure and high-pressure chamber sides; an upper support member which closes an upper opening of the upper cylinder and which has a bearing portion of the rotation shaft; a lower support member which closes a lower opening of the lower cylinder and which has a bearing portion of the rotation shaft; and discharge muffler chambers formed by depressing the outer surfaces of the bearing portions of the respective support members on the side opposite to the respective cylinders to close the depressed portions with covers.
Moreover, a low-pressure refrigerant gas is sucked into the lower cylinder of the first rotary compression element on the side of the low-pressure chamber, and compressed by operations of the roller and vane to obtain an intermediate pressure. The refrigerant gas which has reached the intermediate pressure is discharged from the high-pressure chamber side of the lower cylinder to the discharge muffler chamber via a discharge port. Thereafter, the refrigerant gas is sucked into the upper cylinder of the second rotary compression element on the side of the low-pressure chamber. Then, the refrigerant gas is compressed by the operation of the roller and vane to form a high-temperature high-pressure refrigerant gas, and the gas is discharged from the high-pressure chamber to the discharge muffler chamber (see, e.g., Japanese Patent Application Laid-Open No. 2003-97473).
Here, in the above-described rotary compressor, an O-ring groove is formed in the surface of the bearing portion of the lower support member which abuts on the cover, an O-ring is disposed in the groove, and a gasket is disposed between the cover and the lower support member in an outer peripheral portion of the compressor, thereby constituting a structure in which the discharge muffler chamber is sealed. Here, the cover has to be brought into contact with the support member in the bearing portion, but an interval between the cover and the lower support member has to be set to be equal to a thickness of the gasket to be disposed therebetween in the outer peripheral portion. Therefore, a stepped portion has heretofore been disposed on the surface of the lower support member on the side of the cover. That is, this problem has been handled by protruding an end of the bearing portion as much as the thickness of the gasket on the side of the cover.
However, working of the lower support member becomes complicated, and it is difficult to reduce a dimensional tolerance. This causes a problem that production costs of the rotary compressor suddenly rise, and sealability by the O-ring deteriorates.